Visceral leishmaniasis (VL) remains a major health problem in India. To understand the complex pathogenesis of VL, TMRC examined key questions in epidemiology, immunology and genetics of disease. We developed the resources, infrastructure and manpower necessary for long term research activities. We achieved the major objectives of all 3 projects, obtaining interesting results that have mostly been brought to the scientific community working in related fields. In TRMC II we want to build on the results of TMRC I, to gain greater understanding of the evolution of the human host/pathogen relationship. TMRC II has therefore been divided into 4 major projects with 4 core facilities. Project 1 will be on the determinants of disease progression and role of latent infection in transmission and will study the role of asymptomatic infection in VL at clinical and public health levels. By generating this evidence we expect to be able to inform control programs, as well as clinical decision-making, to decrease spread of disease in the endemic region. We will also be investigating the role of other NTDs in coinfection with VL. Project 2 constitutes studies of the sand fly vector to improve currently inadequate vector control efforts. This project will test a number of hypotheses, challenging current conventions related to the sand fly vector of VL in Bihar, P. argentipes. Project 3 on immune regulation in VL will continue work aimed at understanding the ever evading immunosuppressive pathways that account for severe progression and fatal outcome of untreated VL. In TMRC I, we demonstrated that whole blood of active VL has the capacity to produce antigen specific IFNg and IL-10, which is biologically active in preventing parasite killing. We want to learn how to subvert the activity of IL-10. Project 4 will carry forwad major findings from a GWAS undertaken in TMRC I to determine the molecular and cellular action of HLA class II molecules, which will have major implications for therapeutic intervention and vaccine design. In addition to these projects, there will be a Scientific and Administrative Core A; a Data Management and Biostatistics Core B; a Demographic Surveillance System (DSS) Core C covering over 125,000 people in Muzaffarpur in 2 phases; and a Molecular Typing and Diagnostics Core D. PUBLIC HEALTH RELEVANCE: TMRCII will fully utilize resources developed over 5 years in TMRC l, which brought cutting edge scientific technologies to a developing nation to eradicate a fatal pathogenic disease. The combination of international experts in the fields of epidemiology, immunology, genetics, biostatisticians, along with access to field sites and clinical samples makes it highly likely that the goal of unraveling the complexity of VL will be achieved. Project 1: Determinants of Diseases Progression and Role of Latent Infection in Transmission Project Leader: Kansal, S., MD (Description as provided by applicant): Project 1 Determinants of disease progression and role of latent infection in transmission will study a series of factors that will help understandig why only a limited number of individuals infected with Leishmania donovani develop Visceral Leishmaniasis (VL) on the Indian subcontinent. Project 1 will also contribute to assess the role of asymptomatically infected individuals (those who do not progress to disease) in L. donovani transmission. This project will combine field and laboratory work. Two serological surveys of leishmaniasis infection will be done in high transmission areas to identify recent asymptomatic seroconvertors and controls in the study area (see Core C for details). Similarly, VL cases and controls (i.e. healthy household contacts) will also be identified and included in the different studies. Project 1 is divided in 4 specific aims. Aim 1 will examine the association of HLA-type with seroconversion and disease progression controlling for several confounders identified in the previous risk factor studies. Aim 2 will use a recently developed quantitative PCR to assess parasite load in different subpopulations (i.e. seroconvertors and seronegative individuals) and assess its influence in progression to VL taking into account genetic and environmental factors. Aim 3 will examine the association between co-infections with other Neglected Tropical Diseases (NTD) and VL in two case-control studies. (1) An unmatched case-control study comparing Leishmania seropositives with the general population and (2) a matched case-control study comparing VL cases to community controls will be used to assess the effect of filaria- or geo-helminths L. donovani co-infection on progression to VL. Finally, Aim 4 will contribute to study the role of asymptomatically infected persons by (1) validating a modified SLA-based Quantiferon to detect cellular immune response in asymptomatic individuals and (2) selecting individuals (peripheral blood mononuclear cells (PBMC) culture positive) to be included in the xenodiagnosis experiments (see Project 2 for details) . PUBLIC HEALTH RELEVANCE: Results generated in this project will be of importance for individual as well as for public health. Identifying risk factors for progression from VL infectionto disease may allow for secondary prevention. Evidence on the potential role of asymptomatic infections in L. donovani transmission may have major implications for the current VL control strategy.